<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>7-时钟-中心点</title>
    <style>
        .clock {
  width: 250px;
  height: 250px;
  border: 8px solid #000;
  border-radius: 50%;
  margin: 100px auto;
  position: relative;
}

.line {
  /* 1.定位 */
  position: absolute;
  width: 4px;
  height: 250px;
  background-color: #999;
  left: 50%;
  transform: translate(-50%);
}

/* 线2: 旋转, 每条线旋转角度不同, 单独选中不同的line, 写rotate代码 */
/* 一圈是360度, 等分成  xx 份 */
.line:nth-child(2) {
  transform: translate(-50%) rotate(30deg);
}

.line:nth-child(3) {
  transform: translate(-50%) rotate(60deg);
}

.line:nth-child(4) {
  transform: translate(-50%) rotate(90deg);
}

.line:nth-child(5) {
  transform: translate(-50%) rotate(120deg);
}

.line:nth-child(6) {
  transform: translate(-50%) rotate(150deg);
}

/* 第一根和第四跟宽度大一些 */
.line:nth-child(1),
.line:nth-child(4) {
  width: 5px;
}

/* 遮罩圆形 */
.cover {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 200px;
  height: 200px;
  background-color: #fff;
  border-radius: 50%;
}

/* 表针 */
/* 并集选择器放在单独选择器的上面, 避免transform属性的层叠 */
.hour,
.minute,
.second {
  position: absolute;
  left: 50%;
  /* 盒子底部在盒子中间 */
  bottom: 50%;
}

.hour {
  width: 6px;
  height: 50px;
  background-color: #333;
  margin-left: -3px;
  transform: rotate(15deg);
  transform-origin: center bottom;
}

.minute {
  width: 5px;
  height: 65px;
  background-color: #333;
  margin-left: -3px;
  transform: rotate(90deg);
  transform-origin: center bottom;
}

.second {
  width: 4px;
  height: 80px;
  background-color: red;
  margin-left: -2px;
  transform: rotate(240deg);
  transform-origin: center bottom;
}

/* 螺丝 */
.dotted {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 18px;
  height: 18px;
  background-color: #333;
  border-radius: 50%;
}
    </style>
</head>
<body>
    <div class="clock">
        <!-- 刻度线 -->
        <div class="line"></div>
        <div class="line"></div>
        <div class="line"></div>
        <div class="line"></div>
        <div class="line"></div>
        <div class="line"></div>
      
        <!-- 遮罩圆形 -->
        <div class="cover"></div>
        <!-- 表针 -->
        <div class="hour"></div>
        <div class="minute"></div>
        <div class="second"></div>
      
        <!-- 螺丝 -->
        <div class="dotted"></div>
      </div>
</body>
</html>